C, C++, VB, PHP, Perl, Lisp, VOIP, MySQL, Asterisk, FreeSwitch, Access, BerkelyDB, Linux (many flavors), Unix, Silicon Graphics Irix, Windows 386 through Windows 7+(Win8), Win Server 200x, Dos 1.x to Present, Apache, Bind DNS, Qmail, Sendmail, libDVD, libdvdcss, much more..
Additionally:
Deplyment, Debugging, IP Engineering (Routing & Switching) and VoIP, ISP, Hospitality, Finance, etc..